1. Field of the Invention
The present invention relates to a mobile terminal device equipped with a display, specifically, to a mobile terminal device configured by attaching a thin organic EL display.
2. Description of the Related Art
FIG. 5 is a perspective view of a mobile telephone serving as a mobile terminal device (1) previously disclosed by the applicant. A cabinet (2) equipped with a display (5) is arranged on a supporting box (7) to be slidable in a direction of an arrow D. Operation buttons (70) (70) are arranged on the supporting box (7), so that the device (1) can be operated at an open position in which the operation buttons (70) (70) are exposed.
A device equipped with an organic EL display (5) is disclosed for the display (5) in recent years in view of beauty, thinness, and the like of an image. FIG. 6 is a cross-sectional view of FIG. 5 taken along a perpendicular plane including line A-A. A first recessed surface (20) is formed on an upper surface of the cabinet (2), and a second recessed surface (21) is formed in the first recessed surface (20). At the open position of the cabinet (2), an upper surface end (71) of the supporting box (7) is positioned on a lower side of the display (5), and a rear wall (22) of the cabinet (2) comes into contact with the upper surface end (71) of the supporting box (7).
A transparent cover (4) called a screen made from reinforced glass is attached to the first recessed surface (20), and the organic EL display (5) is fixed to the lower surface of the transparent cover (4) with an adhesive called SVR (Super View Resin). The organic EL display (5) is arranged in the second recessed surface (21).
One sheet of cushion (3) is arranged between the lower surface of the organic EL display (5) and a bottom surface of the second recessed surface (21), and the cushion (3) is attached to both the lower surface of the organic EL display (5) and the upper surface of the rear wall (22). The cushion (3) extends over the entire longitudinal direction of the display (5).
As shown enlarged in FIG. 7, the organic EL display (5) is formed by covering a glass lid body (52), which is formed with a recessed portion (51) at the lower surface, on a glass substrate (50), and glass welding (53) the peripheral edge portion of the lid body (52). The glass (53) for welding has a lower melting point than the glass configuring the lid body (52) and the substrate (50).
A back electrode (54) serving as a cathode is vapor deposited on the substrate (50), and an electron-injection layer, an electron transport layer, a light emission layer, a hole transport layer, a hole injection layer, and an anode (all of which are not shown) positioned in the recessed portion (51) are formed thereon. An interior of the recessed portion (51) is filled with inactive gas to prevent oxidation of the back electrode (54). If the back electrode (54) is oxidized, an image cannot be correctly displayed, and thus the peripheral edge portion of the substrate (50) and the lid body (52) need to be strongly welded (53) to maintain a sealed state so that air does not flow in from the welded portion (53).
It is found, however, that the following points in the above-described mobile terminal device need to be improved.
As shown in FIG. 6, when a downward force is applied to a distal end of the cabinet (2) by a hand of a user at the open position, a bending moment M generates with the end (71) of the supporting box (7) as a center. This bending moment M may cause the rear wall (22) to deflect with a projecting surface facing upward. The cushion (3) is attached to both the lower surface of the organic EL display (5) and the upper surface of the rear wall (22), and is arranged over the entire longitudinal direction of the display (5), and thus the deflection of the rear wall (22) transmits to the cushion (3) as is thereby deflecting the entire cushion (3). Such deflection is transmitted to the organic EL display (5), whereby a force of detaching the welding of the substrate (50) and the lid body (52) of the organic EL display (5) acts. The welded portion (53) thereby detaches, air flows into the recessed portion (51), and an image may not be correctly displayed.
It is an object of the present invention to provide a device capable of maintaining a sealed state of the organic EL display (5) and correctly displaying an image even if a bending moment M is applied on the cabinet (2).